AUGUSTA, Ga. -- For the second consecutive week, Bill Haas has gone low in the first round.

Unlike last week, he hopes to avoid a collapse in the final three days.

Haas opened with a 4-under 68, the first time he's broken 70 in 17 career rounds at Augusta National. That set the early tone Thursday.

A week ago, Haas opened with a 65 to take the first-round lead at the Shell Houston Open. He failed to break par the next three days, shooting 74-76-72. So he's well aware that things can go south in a hurry, especially in the pressurized environment of the year's first major.

"I know there's tons of golf left," Haas said. "And maybe understanding that, I know that I can't expect too much. You've just got to go out there and keep playing golf, try to hit that fairway on No. 1 tomorrow."

Haas, the 2011 FedExCup champ, struck a poor approach at the opening hole and suffered a bogey. But he bounced back with a 15-foot birdie putt and made another birdie at four that felt "almost like an eagle," he said. "That hole is so difficult."

He saved par with a 12-foot putt at the fifth hole. With a hot putter and his nerves calmed, he played the rest of the round in 3 under.

"I easily could have still been 1 over," Haas said about the first five holes. "The putter kind of saved me and settled me down."